The present invention relates to a novel driving device consisting of a stator and an armature which can be moved in two dimensions along the stator, and to a two-dimensional driving device used as a positioning device in a semiconductor manufacturing process.
Heretofore, in positioning devices used in semiconductor manufacturing apparatus, generally a loading table is adapted to be moved each time by a microfine distance, and as driving means for the loading table a step motor or a rotary type D.C. servo motor is used. In general the rotary motion of the servo motor is converted to linear motion by a feed screw or the like. However, in view of the structure of the prior art apparatus it is difficult to give a fine movement of 1 micron or less to the loading table, and if it is intended to obtain a high resolution, generally the moving speed becomes slow due to the fact that a pitch of a screw becomes fine. Therefore, in many examples a loading table is formed in a double structure having a separate structure for providing a fine displacement. Hence, the device becomes mechanically complex, and expensive. On the other hand, there have been recent developments in D.C. linear motors and good results have been obtained both in obtaining high resolution of 1 micron or less and in high speed feeding using linear motors. However, both the method relying upon screw feed and the method employing a linear motor can give only a linear motion to a loading table. Nevertheless, generally in many cases a loading table must achieve two dimensional motion along a plane, and therefore, it has been a common practice to form an X-Y orthogonal coordinate system by making use of two linear drive sources which are perpendicular to each other and guide rails for restraining movements in the direction other than the driving directions.
The inventor of this invention previously invented a novel driving device for resolving the above-mentioned problem, and also invented a positioning device making use of the driving device. A Japanese patent application for the invention is pending at the Japanese Patent Office as Patent Application No. 56344/1982 and is also filed at the U.S. Patent Office claiming a Convention Priority. The U.S. application was filed on Apr. 1, 1983, Ser. No. 481,324, entitled Two-Dimensional Precise Positioning Device for Use in a Semiconductor Manufacturing Apparatus and has a common assignee.
According to this prior invention, a novel driving device which was not found in the past can be provided, and by making use of this driving device a high speed and precise positioning device can be provided without relying upon a double structure or guide rails.
However, in the device according to the prior invention, a control circuit for controlling the device becomes complex, and hence manufacture and handling of the device are troublesome.
The present invention improves the aforementioned prior invention, and it is one object of the present invention to provide a novel current-motion converter in which a control method and a control circuit are relatively simple.
Another object of the present invention is to provide a driving device for use in a precision positioning device or the like by making use of the current-motion converter.